The present invention relates to a shaft seal for a gas pumping device.
The gas to be pumped by a gas pumping device is sometimes either expensive or dangerous. In such a case there is a requirement that the pump chamber is completely sealed off from the surrounding atmosphere. According to prior art this has been obtained through arranging two seals between the pump chamber and the slider bearing in which the shaft end of the rotatable pumping element is journalled. The chamber between the two seals is then supplied with liquid whose pressure is somewhat higher than the gas pressure so that no leakage of gas occurs.